This invention relates in general to gaskets for providing a seal between two mating components and in particular to an improved gasket having a closure assembly secured over a port formed therethrough for thermally sealing and insulating one of the components from the other.
Gaskets are well known articles which are adapted to provide a relatively leak-proof seal between two mating components. Typically, the two components are formed having respective flat surfaces which are disposed adjacent to one another during use. During assembly of the components, a gasket is placed between the mating flat surfaces. Bolts or similar means are utilized to connect the two components together and compress the gasket between the mating surfaces. When compressed in this manner, the gasket effects a relatively leak-proof seal between the two components.
One common application for gaskets is between the intake manifolds and cylinder heads of internal combustion engines. Such manifold gaskets are typically formed having a plurality of ports or openings for accommodating the passage of various gases and fluids between the intake manifold and the cylinder head. For example, gasket ports are usually provided for permitting the flow of the gaseous fuel/air mixture and the fluid engine coolant through respective aligned passageways formed in the intake manifold and the cylinder head. The fuel/air mixture passing through the gasket intake port is typically relatively cool and in a vacuum state, while the engine coolant is typically quite hot and pressurized. Also, hot oil is sealed in the valleys of V-style engines. Thus, manifold gaskets are frequently exposed to a wide range of temperatures, pressures, and corrosive materials during normal use. Manifold gaskets are also typically provided with a peripheral sealing structure, such as a molded elastomeric bead, for providing a relatively leak-proof seal between the intake manifold and the cylinder head.
On internal combustion engines which are equipped with a carburetor or throttle body fuel injection apparatus, it is known to circulate hot exhaust gases from the cylinder head through the intake manifold. Such exhaust gas recirculation is performed to rapidly heat the intake manifold when the engine is cold so as to enhance the combustion process. To accomplish this, aligned passageways are formed in the intake manifold and the cylinder head to pass the exhaust gases therethrough. Consequently, it is known to provide a corresponding exhaust gas recirculation port through the gasket to accommodate this exhaust gas recirculation.
However, some internal combustion engines are equipped with a fuel injection apparatus which injects the fuel directly into the cylinder. In these types of engines, there is no need to heat the intake manifold. Thus, it is unnecessary to provide any exhaust gas recirculation through the intake manifold. Without the need for such heating, the intake manifold can be formed from non-metallic materials, such as plastic, which are otherwise susceptible to damage from heat. These non-metallic materials provide intake manifolds which are significantly lighter and less expensive than conventional metallic intake manifolds.
Unfortunately, for the sake of economy, vehicle manufacturers typically provide only a single cylinder head structure which is adapted for use in both types of engines, i.e., engines which do and do not recirculate hot exhaust gases through the intake manifold. Thus, these cylinder heads are usually all provided with a passageway for circulating the hot exhaust gases through the intake manifold. As mentioned above, the non-metallic intake manifolds of engines which do not employ such exhaust gas recirculation are often formed from plastic or similar materials which are susceptible to damage from heat. Thus, in those engines having non-metallic intake manifolds, it is necessary to provide some means for preventing the hot exhaust gases from contacting the intake manifold.